// SPDX-License-Identifier: GPL-2.0-only
/*
 * Designware HDMI CEC driver
 *
 * Copyright (C) 2015-2017 Russell King.
 */
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include <drm/drm_edid.h>
#include <drm/bridge/dw_hdmi.h>

#include <media/cec.h>
#include <media/cec-notifier.h>

#include "dw-hdmi-cec.h"

enum {
    HDMI_IH_CEC_STAT0 = 0x0106,
    HDMI_IH_MUTE_CEC_STAT0 = 0x0186,

    HDMI_CEC_CTRL = 0x7d00,
    CEC_CTRL_START = BIT(0),
    CEC_CTRL_FRAME_TYP = 3 << 1,
    CEC_CTRL_RETRY = 0 << 1,
    CEC_CTRL_NORMAL = 1 << 1,
    CEC_CTRL_IMMED = 2 << 1,

    HDMI_CEC_STAT = 0x7d01,
    CEC_STAT_DONE = BIT(0),
    CEC_STAT_EOM = BIT(1),
    CEC_STAT_NACK = BIT(2),
    CEC_STAT_ARBLOST = BIT(3),
    CEC_STAT_ERROR_INIT = BIT(4),
    CEC_STAT_ERROR_FOLL = BIT(5),
    CEC_STAT_WAKEUP = BIT(6),

    HDMI_CEC_MASK = 0x7d02,
    HDMI_CEC_POLARITY = 0x7d03,
    HDMI_CEC_INT = 0x7d04,
    HDMI_CEC_ADDR_L = 0x7d05,
    HDMI_CEC_ADDR_H = 0x7d06,
    HDMI_CEC_TX_CNT = 0x7d07,
    HDMI_CEC_RX_CNT = 0x7d08,
    HDMI_CEC_TX_DATA0 = 0x7d10,
    HDMI_CEC_RX_DATA0 = 0x7d20,
    HDMI_CEC_LOCK = 0x7d30,
    HDMI_CEC_WKUPCTRL = 0x7d31,
};

struct dw_hdmi_cec {
    struct dw_hdmi *hdmi;
    const struct dw_hdmi_cec_ops *ops;
    u32 addresses;
    struct cec_adapter *adap;
    struct cec_msg rx_msg;
    unsigned int tx_status;
    bool tx_done;
    bool rx_done;
    struct cec_notifier *notify;
    int irq;
};

static void dw_hdmi_write(struct dw_hdmi_cec *cec, u8 val, int offset)
{
    cec->ops->write(cec->hdmi, val, offset);
}

static u8 dw_hdmi_read(struct dw_hdmi_cec *cec, int offset)
{
    return cec->ops->read(cec->hdmi, offset);
}

static int dw_hdmi_cec_log_addr(struct cec_adapter *adap, u8 logical_addr)
{
    struct dw_hdmi_cec *cec = cec_get_drvdata(adap);

    if (logical_addr == CEC_LOG_ADDR_INVALID) {
        cec->addresses = 0;
    } else {
        cec->addresses |= BIT(logical_addr) | BIT(0x0f);
    }

    dw_hdmi_write(cec, cec->addresses & 0xff, HDMI_CEC_ADDR_L);
    dw_hdmi_write(cec, cec->addresses >> 0x8, HDMI_CEC_ADDR_H);

    return 0;
}

static int dw_hdmi_cec_transmit(struct cec_adapter *adap, u8 attempts, u32 signal_free_time, struct cec_msg *msg)
{
    struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
    unsigned int i, ctrl;

    switch (signal_free_time) {
        case CEC_SIGNAL_FREE_TIME_RETRY:
            ctrl = CEC_CTRL_RETRY;
            break;
        case CEC_SIGNAL_FREE_TIME_NEW_INITIATOR:
        default:
            ctrl = CEC_CTRL_NORMAL;
            break;
        case CEC_SIGNAL_FREE_TIME_NEXT_XFER:
            ctrl = CEC_CTRL_IMMED;
            break;
    }

    for (i = 0; i < msg->len; i++) {
        dw_hdmi_write(cec, msg->msg[i], HDMI_CEC_TX_DATA0 + i);
    }

    dw_hdmi_write(cec, msg->len, HDMI_CEC_TX_CNT);
    dw_hdmi_write(cec, ctrl | CEC_CTRL_START, HDMI_CEC_CTRL);

    return 0;
}

static irqreturn_t dw_hdmi_cec_hardirq(int irq, void *data)
{
    struct cec_adapter *adap = data;
    struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
    unsigned int stat = dw_hdmi_read(cec, HDMI_IH_CEC_STAT0);
    irqreturn_t ret = IRQ_HANDLED;

    if (stat == 0) {
        return IRQ_NONE;
    }

    dw_hdmi_write(cec, stat, HDMI_IH_CEC_STAT0);

    if (stat & CEC_STAT_ERROR_INIT) {
        cec->tx_status = CEC_TX_STATUS_ERROR;
        cec->tx_done = true;
        ret = IRQ_WAKE_THREAD;
    } else if (stat & CEC_STAT_DONE) {
        cec->tx_status = CEC_TX_STATUS_OK;
        cec->tx_done = true;
        ret = IRQ_WAKE_THREAD;
    } else if (stat & CEC_STAT_NACK) {
        cec->tx_status = CEC_TX_STATUS_NACK;
        cec->tx_done = true;
        ret = IRQ_WAKE_THREAD;
    }

    if (stat & CEC_STAT_EOM) {
        unsigned int len, i;

        len = dw_hdmi_read(cec, HDMI_CEC_RX_CNT);
        if (len > sizeof(cec->rx_msg.msg)) {
            len = sizeof(cec->rx_msg.msg);
        }

        for (i = 0; i < len; i++) {
            cec->rx_msg.msg[i] = dw_hdmi_read(cec, HDMI_CEC_RX_DATA0 + i);
        }

        dw_hdmi_write(cec, 0, HDMI_CEC_LOCK);

        cec->rx_msg.len = len;
        smp_wmb();
        cec->rx_done = true;

        ret = IRQ_WAKE_THREAD;
    }

    return ret;
}

static irqreturn_t dw_hdmi_cec_thread(int irq, void *data)
{
    struct cec_adapter *adap = data;
    struct dw_hdmi_cec *cec = cec_get_drvdata(adap);

    if (cec->tx_done) {
        cec->tx_done = false;
        cec_transmit_attempt_done(adap, cec->tx_status);
    }
    if (cec->rx_done) {
        cec->rx_done = false;
        smp_rmb();
        cec_received_msg(adap, &cec->rx_msg);
    }
    return IRQ_HANDLED;
}

static int dw_hdmi_cec_enable(struct cec_adapter *adap, bool enable)
{
    struct dw_hdmi_cec *cec = cec_get_drvdata(adap);

    if (!enable) {
        dw_hdmi_write(cec, ~0, HDMI_CEC_MASK);
        dw_hdmi_write(cec, ~0, HDMI_IH_MUTE_CEC_STAT0);
        dw_hdmi_write(cec, 0, HDMI_CEC_POLARITY);

        cec->ops->disable(cec->hdmi);
    } else {
        unsigned int irqs;

        dw_hdmi_write(cec, 0, HDMI_CEC_CTRL);
        dw_hdmi_write(cec, ~0, HDMI_IH_CEC_STAT0);
        dw_hdmi_write(cec, 0, HDMI_CEC_LOCK);

        dw_hdmi_cec_log_addr(cec->adap, CEC_LOG_ADDR_INVALID);

        cec->ops->enable(cec->hdmi);

        irqs = CEC_STAT_ERROR_INIT | CEC_STAT_NACK | CEC_STAT_EOM | CEC_STAT_DONE;
        dw_hdmi_write(cec, irqs, HDMI_CEC_POLARITY);
        dw_hdmi_write(cec, ~irqs, HDMI_CEC_MASK);
        dw_hdmi_write(cec, ~irqs, HDMI_IH_MUTE_CEC_STAT0);
    }
    return 0;
}

static const struct cec_adap_ops dw_hdmi_cec_ops = {
    .adap_enable = dw_hdmi_cec_enable,
    .adap_log_addr = dw_hdmi_cec_log_addr,
    .adap_transmit = dw_hdmi_cec_transmit,
};

static void dw_hdmi_cec_del(void *data)
{
    struct dw_hdmi_cec *cec = data;

    cec_delete_adapter(cec->adap);
}

static int dw_hdmi_cec_probe(struct platform_device *pdev)
{
    struct dw_hdmi_cec_data *data = dev_get_platdata(&pdev->dev);
    struct dw_hdmi_cec *cec;
    int ret;

    if (!data) {
        return -ENXIO;
    }

    /*
     * Our device is just a convenience - we want to link to the real
     * hardware device here, so that userspace can see the association
     * between the HDMI hardware and its associated CEC chardev.
     */
    cec = devm_kzalloc(&pdev->dev, sizeof(*cec), GFP_KERNEL);
    if (!cec) {
        return -ENOMEM;
    }

    cec->irq = data->irq;
    cec->ops = data->ops;
    cec->hdmi = data->hdmi;

    platform_set_drvdata(pdev, cec);

    dw_hdmi_write(cec, 0, HDMI_CEC_TX_CNT);
    dw_hdmi_write(cec, ~0, HDMI_CEC_MASK);
    dw_hdmi_write(cec, ~0, HDMI_IH_MUTE_CEC_STAT0);
    dw_hdmi_write(cec, 0, HDMI_CEC_POLARITY);

    cec->adap = cec_allocate_adapter(&dw_hdmi_cec_ops, cec, "dw_hdmi", CEC_CAP_DEFAULTS | CEC_CAP_CONNECTOR_INFO,
                                     CEC_MAX_LOG_ADDRS);
    if (IS_ERR(cec->adap)) {
        return PTR_ERR(cec->adap);
    }

    dw_hdmi_set_cec_adap(cec->hdmi, cec->adap);

    /* override the module pointer */
    cec->adap->owner = THIS_MODULE;

    ret = devm_add_action(&pdev->dev, dw_hdmi_cec_del, cec);
    if (ret) {
        cec_delete_adapter(cec->adap);
        return ret;
    }

    ret = devm_request_threaded_irq(&pdev->dev, cec->irq, dw_hdmi_cec_hardirq, dw_hdmi_cec_thread, IRQF_SHARED,
                                    "dw-hdmi-cec", cec->adap);
    if (ret < 0) {
        return ret;
    }

    cec->notify = cec_notifier_cec_adap_register(pdev->dev.parent, NULL, cec->adap);
    if (!cec->notify) {
        return -ENOMEM;
    }

    ret = cec_register_adapter(cec->adap, pdev->dev.parent);
    if (ret < 0) {
        cec_notifier_cec_adap_unregister(cec->notify, cec->adap);
        return ret;
    }

    /*
     * CEC documentation says we must not call cec_delete_adapter
     * after a successful call to cec_register_adapter().
     */
    devm_remove_action(&pdev->dev, dw_hdmi_cec_del, cec);

    return 0;
}

static int dw_hdmi_cec_remove(struct platform_device *pdev)
{
    struct dw_hdmi_cec *cec = platform_get_drvdata(pdev);

    cec_notifier_cec_adap_unregister(cec->notify, cec->adap);
    cec_unregister_adapter(cec->adap);

    return 0;
}

static struct platform_driver dw_hdmi_cec_driver = {
    .probe = dw_hdmi_cec_probe,
    .remove = dw_hdmi_cec_remove,
    .driver =
        {
            .name = "dw-hdmi-cec",
        },
};
module_platform_driver(dw_hdmi_cec_driver);

MODULE_AUTHOR("Russell King <rmk+kernel@armlinux.org.uk>");
MODULE_DESCRIPTION("Synopsys Designware HDMI CEC driver for i.MX");
MODULE_LICENSE("GPL");
MODULE_ALIAS(PLATFORM_MODULE_PREFIX "dw-hdmi-cec");
